I THINK that you can only scale walls in ANY Pokemon game if you have an Action-Replay or any other hacker. Although I've heard that if you get the steps wrong it can conjure up errors in your saved data.
you have to have action replay
on Pokemon diamond and pearl you will need the explore kit to go underground then after mining the walls for loot there is a chance you may find a heart scale also fosils and evoloution stones
Wild horsea sometimes have it.
rock climb from Pokemon 2007
Search for them in the walls underground.
In pastoria city you can find the move tutor. You need a heart scale before he will teach you a move and can find them in the underground by digging into walls.
defeat red gyarados.
You can go under ground
walk through walls
its inside pastroia city.
No, it is not possible.
You cant! its a cheat